Con Rod bolt torque

[burtco99]

I need to verify the correct connecting rod bolt torque specs for a 1982 20hp Johnson (crossflow 31.8ci)

The two sources I have tell me 348-372 inch pounds (29-31 ft pounds). That sounds high for the size of bolt in the con rod. Can someone confirm this is the correct torque to use?

Also, do I use oil on the threads, or is it recommended to use loctite on the con rod bolts?

Thanks,
Les Burt

[zul8tr]

That torque seems high but I don't have a value for the J engine. The 20hp Mercs use 180 in lbs. Yes on the Locktite use the red but not an overdose. Are the nuts nylock type?

[burtco99]

No nuts. The bolt threads into the con rod. These bolts are unique in that they have a 5/16-24 thread, but have a reduced diameter waist (1/4") between the threads and bolt head.

[zul8tr]

That reduced diameter is a rolled thread bolt arguably stronger than cut threads. The 5/16 - 24 could be in the 14 - 27 ft lbs area but you still need to get the Johnson spec because the torque is dependent on the metal grade of the bolt and if dry or lubed, etc. As an example here is a table as a guide:

http://www.americanboltcorp.com/tech/techtorque.pdf

[Barry Strawn]

The 1982 factory manual says 29-31 ft. lbs (40-42 Nm) for the connecting rod screws.